Horn and howler for marine and naval use



June 1935. "r. JESSEN 2,006,021

non! AND BOILER FOR MARINE AND NAVAL usn Filed Aug. 15, 193:5

Z v z l/VVE/YTOR Patented June 25, 1-935 UNITED-i STATES HORN AND HOWLEB FOR MARINE AND NAVAL USE Theodor lessen, Altona-Bahrenfcld, Germany Application August 15, 1933, Serial No. 685,272

, In Germany January 30, 1933 4 Claims.

My invention relates to improvements in the horns for howlersfor marine and naval use and more particularly in motor driven howlers of the type in which the sound is produced by means of 5 a piston adapted to be reciprocated at the bottom end of the horn at a velocity such that the naturaloscillations of the column of air within the horn are in resonance with the movement of the piston, and in which means are provided to give sharply accentuated audible signals as prescribed by international marine signal-code, so as to enable the emission of Morse codesignals or impulses within short intervals. of time.

In a construction now in use this has been attained by inserting a magnetic friction-coupling between the motor and the crank-gear with sound generating piston, thus, when giving consecutive sound signals only the small masses of the piston and the crank gear must beaccelerated to full speed, whilst the large rotating masses of the motor, which are already set running in advance,

friction coupling is an important part of the mechanism and it must be adapted to transmit comparatively high power which in a howler heretofore constructed amounts to 8 HP with 75 os- 'cillations per second of the piston. Therefore the said coupling'must be very carefully manufac- 'tured in order that it may satisfy the demand particularly when the fog lasts for a long time. How ever, so far, troubles in the operation of the apparatus'couldnot surely be avoided by reason of the strong vibrations thereof.

The object of the improvements is to provide a horn which is especially reliable in operation and which may be manufactured at lowest possible cost. My invention is based on the fact that for generating a sound by means of resonance of the column of air a definite and comparatively high number of reciprocations of the piston is needed, and that the sound is produced only when the number of oscillations of resonance is attained, and that the sound is interrupted when this number .01 reciprocations of the piston is slightly reduced: In a similar way the sound is interrupted when this number of oscillations is slightly exceeded. Thus the range of number oi. vibrations orrecipr'ocations of the piston within which the sound is produced varies within nar row limits.

, In my improved horn the magnetic friction .coupling is dispensed with, and the reciprocating piston with crank gear is permanently connected with the driving motor (appropriately this may be an electromotor, but it may be also of another type) for producing well-defined sounds in rapid succession the crank mechanism is not arrested in the periods of time between the successive sounds, but the number of reciprocations 'dependent on the numbr of revolutions of the motor is but slightly reduced by switching resistance into the armature circuit of an electromotor, so that the resonance between the vibrations of the piston and the natural oscillations of the column of air is disturbed. While the system is operated at the said reduced number of revolutions the motor, and thus the crank gear and the piston too are in a certain sense in a position ready for action. 20

Now, for emitting sounds the motor can be brought suddently to full working speed (resonance speed) from ready-for-action speed by simply switching-over to full working voltage; this produces suddenly a well-defined sound with full power which is maintained as long as the motor is connected to the working voltage. The sound is broken merely by re-switching the motor toready-for-action voltage. In this case, the column of air which reacts on the piston while the sound is being produced, the reaction of which must be overcome by the full output of the motor (which is 8 HP in the example referred to above) will suddenly reduce the velocity so far that the piston and the oscillating column of air will be brought out of synchronism, thus the sound is suddenly interrupted from its full power in an abrupt manner.

In contrast with prior devices in which a clutch or magnetic friction coupling between the 40 driving motor and the vibrating member or piston was used in an attempt to produce sharp, abrupt sounds for signalling, my invention dispenses with such magnetic couplings, the driving motor and piston of the horn beingpermanently connected by a crank arrangement and the same abrupt sounds are obtained by simply switching over the electrical driving motor from the readyfor-actionvoltage to the working voltage and vice versa. 0

In a howler constructed according tomy invention and performing oscillations persecond, thenormal number of revolutions of the crank needed for producing the sound is 4500 per min- We. and the reduced number or revolutions 55 (ready-for-action position) with which the piston does not produce a sound is 3800 per minute. The energy of a moving body is mass velocity velocity 2 and therefore for accelerating the system fromthe ready-for-action state to the sound producing or working state only A; of the power must be applied which would be necessary for starting the motor from at-rest to the working state. Thus the motor can be changed-over from its ready-for-action speed in one step, that is directly, to the full working voltage, reaching full speed, i. e. the necessary resonance-speed, practically instantaneously without giving rise to an unduly great surge of current.

"For the purpose of explaining the invention an example embodying the same has been shown in the accompanying drawing, in which, the same reference characters have been used in all the views to indicate correspondingparts. In said Fig; l is a diagram showing the curve of the resonance of a horn constructed by me in which the piston performs 75 vibrations per second and the power of the motor is 8 HP, the current consumption of the motor being ploted' as a function of the number of revolutions.

Fig. 2 is a sectional elevation showing the horn, and

Fig. 3 is a diagram showing the electrical. connection of the horn.

As appears from Fig. l, the full resonance and the full sound are obtained 'at a number of revolutions (of the motor) of 4500 per minute and" at this velocity the current consumption and the intensity of the, sound attain their maximum. When the number of revolutions is slightly reduced, say to 3800 per minute, no sound is proanism under substantially-no load.

The dotted part of the diagram shows that a similar result may be obtained when the number of revolutions of the motor is increased beyond that corresponding to the resonance. For practical reasons the numberof revolutions will, of course, be reduced for breaking the sound.

As appears from Fig. 2, the horn or howler comprises a sound tube or resonator R and a piston K which is adapted to be reciprocated by the crank T connected with an electromotor M by means of a direct coupling D.

Fig. 3 shows the diagram of connection of the motor. The motor M is connected in series with a rheostat comprising terminals S S S and S and a switch lever H. The terminals S and S are the usual terminalsfor starting the motor,

the terminal S corresponds to the state in which the system is ready for action, and the terminal S corresponds to the working state of the motor.

Ofcourse, any suitable number of terminals S and 53 may be provided as may be necessary for interrupting the sound only shifting of the switch lever H from one terminal to another one is .needed. It will be understood that the switch arrangement illustrated in Fig. 3 has been shown merely as an example and that other starting advisable for use in case of long lasting fog for.

giving a definite sequence of signals in definite periods of time.

It will be understood that the operation of the horn is simple and reliable, because it requires only shifting of the switch lever and the motor instantaneously changes its velocity.

I claim:

l. A horn, comprising, in combination, a resonator providing an air column having a definite natural period of oscillation, a vibrating-member disposed at the inner end of saidresonator, means for'vibrating said member continuously and at selectively variable rates into and out of the range of frequency that will produce an audible tone by resonance with said air column, said means being under the control of the operator of said horn and directly connected with said vibrating member, whereby an intermittently audible.

'means under control of the operator of said horn and directly connected with said vibrating member for continually vibrating said member, means for positively regulating the speed of said power means to abruptly vary the rate of vibration of said member into and out of. the range of frequency that will produce an audible tone by resonance with said air column, whereby an intermittently audible signal may be produced without cessation of operation of said vibrating member.

3. A horn, comprising, in combination, a resonator providing an air column having a definite natural period of oscillation, a continually reciprocating piston disposed at the inner end of said resonator, an electric motor means for .continually reciprocating said piston, rheostat means for positively varying the speed of said motor to vary the rate of reciprocation of said piston into and out of the range of frequency that will produce an audible tone by resonance with said air column,

whereby intermittent and alternate periods of audibility and silence may be efiected without cessation of operation of said piston and motor.

4. A horn, comprising, in combinationa reso-' nator providing an air column having a definite natural period of oscillation, a continually reciprocating piston disposed at the inner end of said resonator, a motor means for continually reciprocating said piston, motor controlling means for positively varying the speed of said motor to vary the rate of reciprocation of said piston into and out of the range of frequency that will produce an audible tone by resonance with said air col-, umn, whereby intermittent and alternate periods of audibility and silence may be effected without cessation of operation of said piston and motor.

1 l I THEODOR JESSEN. 

